Cloudflare Tunnel - Error 526 - Insecure Upstream

Hi All

Hope something can help or guide me.

Making use of Cloudflare Zero Trust / Tunneling services and was working great the last couple of months. I make use of the WARP Client that connects to my teams channel and then access my internal applications through the app launcher.

Being great thus far, but notice today that all my apps is giving Error 526 Insecure Upstream / HTTP Response Code: 526

No settings has been changed. All certificates on the devices are loaded. Read through all the guides, tried different http policy but nothing seems to work.

Any ideas?